Polyaryl ether ketones are excellent in chemical resistance, acid resistance, alkali resistance, dimensional stability and mechanical characteristics, and have been studied as engineering plastics, fibers, films, matrices for composite materials, etc.
As a polyaryl ether ketone, a polymer wherein an aryl group is a phenylene group has been so far well known.
Namely, there have been known a process in which a polyaryl ether ketone comprising recurring units represented by formula (a) ##STR2## is produced by reacting 4,4'-dihalobenzophenone with hydroquinone (Japanese Laid-open Patent Appln. No. 90296/1979), a process in which a polyaryl ether ketone comprising recurring units represented by formula (b) ##STR3## is produced by reacting 4,4'-dihalobenzophenone with 4,4'-dihydroxybenzophenone (Japanese Patent Publication No. 22939/ 1982), and a process in which a polyaryl ether ketone comprising recurring units represented by formula (c) ##STR4## is produced by reacting bis(p-halobenzoyl)benzene with hydroquinone (Japanese Laid-open Patent Application Nos. 34900/1978 and 97094/1978).
Heat resistance of these polyaryl ether ketones is not altogether enough, and development of polyaryl ether ketones having excellent heat resistance has been demanded.
Japanese Laid-open Patent Application No. 29427/1989 discloses an aromatic polyketone copolymer comprising 15 to 90 mol % of structural units represented by formula (d) ##STR5## and 10 to 85 mol % of structural units presented by formula (e)
Japanese Laid-open Patent Application No. 33132/1989 discloses an aromatic polyketone copolymer comprising 50 to 85 mol % of structural units represented by formula (e) and 15 to 50 mol % of structural units represented by formula (f) ##STR6##
Japanese Laid-open Patent Application No. 33132/1989 involves an aromatic polyketone copolymer comprising 15 to 40 mol % of structural units represented by formula (g) ##STR7## and 60 to 85 mol % of structural units represented by formula (h) ##STR8##
W089/04848 internationally laid open on Jun. 1, 1989 includes an arylene ether ketone copolymer comprising
(a) 99 to 10 mol % of recurring units represented by formula (I) ##STR9## and
(b) 1 to 90 mol % of recurring units represented by formula (II) EQU --Ar--O--Ar--CO-- (II)
wherein each Ar denotes a m-phenylene group, a p-phenylene group, or a di-m-phenylene group, a di-p-phenylene group, a poly-m-phenylene group or a poly-p-phenylene group in which plural phenylene rings are bound together by a direct bond, --O-- or --CO--,
and a homopolymer comprising only the recurring units of formula (I).
However, W089/04848 does not describe at all a homopolymer wherein the recurring units of formula (I) are those represented by the following formula: ##STR10## Moreover, the present inventors have found that the homopolymer comprising the recurring units represented by the above formula is not obtained by a process in which a corresponding naphthalenedicarboxylic acid halide is reacted with 4,4'-diphenoxybenzene.
Poly(arylene ether ketones) are crystalline, heat-resistant thermoplastic resins and are known to be excellent in heat resistance, chemical resistance and electrical properties; they are being developed as engineering plastics making use of these profitable characteristics. Accordingly, formation of fibers from poly(arylene ether ketones) has industrially great significance.
Examples of formation of fibers from poly(arylene ether ketones) are still limited nowadays. While fibers of polyether ether ketones (PEEK) are described in Japanese Laid-open Patent Application Nos. 191,322/1982 and 231,016/1987, and Sen-i Gakkaishi vol. 41, 59 (1985), vol. 43, 507 (1987) and vol. 45, 509 (1989). Fibers of polyether ketones (PEK) are disclosed in Japanese Patent Publication No. 33,419/81.
The poly(arylene ether ketone) fibers disclosed in the above known literature are hardly said to have sufficient mechanical properties, and their Young's modulus remains at a low level compared with e.g. commercial polyester fibers. Moreover, a glass transition temperature of a starting material is 143.degree. C. in PEEK and 154.degree. C. in PEK. Fibers formed from melt-moldable poly(arylene ether ketones) having a higher glass transition temperature have been thus expected.
Regarding the poly(arylene ether ketones) which are being developed as engineering plastics as stated above, formation of films therefrom has also industrially great significance.
Examples of films of poly(arylene ether ketones) are still limited at present. While fibers of polyether ether ketones (PEEK) are described in Japanese Laid-open Patent Application Nos. 137,166/1978, 63,417/1983 and 1,879,284/1985, but examples of films of poly(arylene ether ketones) other than PEEK are few.
PEEK has the aforesaid excellent properties but its glass transition temperature is 143.degree. C. Films of melt-moldable poly(arylene ether ketones) having a higher glass transition temperature have thus been demanded.